The present invention relates to a new and improved construction of a control circuit for the ignition of a low-ohm ignition capsule or pill by means of a power switch and containing a voltage source.
A state-of-the-art control circuit of this type has been disclosed in German Pat. No. 2,750,972. This circuit serves for controlling low-ohm loads by means of a power switch connected with a current source, especially for controlling low-ohm ignition capsules in ignition circuits.
If such circuitry is used in conjunction with a projectile where there is available a supply or feed capacitor as the current source, which first is charged by a current generator upon firing of the projectile, then it is necessary to undertake certain protective measures, namely:
(a) it is necessary to prevent that, upon charging of the supply capacitor, the ignition capsule will be ignited before there has been attained a minimum voltage. PA1 (b) upon malfunction of the supply capacitor there is present the danger that because of a rapid speed of ascent or rise of the voltage there will occur a premature ignition of the ignition capsule, especially if there are present undesired spurious signals. PA1 (a) an ignition or supply capacitor is provided which can be charged by the supply voltage, the ignition capacitor being connected with the power switch and with the ignition capsule; PA1 (b) there is provided a static blocking circuit which prevents ignition of the ignition capsule as long as the ignition capacitor is being charged, and a transistor connects the base of the power switch with ground; PA1 (c) a static delatching circuit is provided which eliminates the blocking action as soon as the ignition capacitor has been charged, and a Zener diode serves to switch-off the static blocking circuit as soon as the voltage of the ignition capacitor has reached a threshold value of the Zener diode; and PA1 (d) a dynamic blocking circuit is provided which, upon malfunction or failure of the ignition capacitor, prevents an unintentional ignition of the ignition capsule
With the aforementioned prior art control circuit there are not provided any protective devices which preclude any premature ignition of the ignition capsule or the like in the event that there arises any one or both of the aforementioned situations.